Listing Status

Physical Description

The least tern is the smallest tern in North America. Least terns can reach a length between 8.3-9.1 inches (21-23 centimeters) with a wingspan of 21-23 inches (53-58 centimeters) (Thompson et al., 1997). Least terns have long pointed wings and a deeply forked tail. Other physical characteristics include a yellow beak, gray back, white belly, and black cap.

Life History

The least tern’s diet primarily consists of fish, but they will also feed on small invertebrates. (The Cornell Lab of Ornithology, 2011).

Male least terns have a unique courtship ritual. During courting, the male will offer the female food in hopes of gaining her choice as a mate. Once the two mates are together they will begin building the nest in shallow depressions in bare beach sand. Least terns will also build nests on gravel rooftops. Least terns lay eggs between the middle of April and the beginning of May. The eggs are camouflaged to help prevent predation. Egg incubation lasts for 21 days. Young least terns are able to leave the nest three to four days after hatching.

Habitat and Distribution

The least tern inhabits areas along the coasts of Florida including estuaries and bays, as well as areas around rivers in the Great Plains (Florida Natural Areas Inventory 2001). In Florida, the least tern can be found throughout most coastal areas. Outside of Florida, least terns are found along the U.S. Atlantic Coast, mid Atlantic states, and down from Mexico to northern Argentina (Florida Natural Areas Inventory 2001).

Threats:

The least tern faces many threats as the human population increases along the coasts. The main threat to the least tern population is habitat loss. Loss of habitat is often attributed to coastal development. Coastal development causes damage to least tern habitat because of the building on the coasts, human traffic on the beaches, and recreational activities. Increased numbers of predators due to the larger amounts of available food and trash for scavenging are also a threat to the least tern. Predators can cause destruction to breeding colonies while they are nesting by destroying nests and eating chicks and eggs. Also, global climate change is an impending threat to the least tern. Rising sea levels and more frequent strong storms may damage and destroy least tern nests, as well as habitat. Spring tides can also cause flooding of least tern nests. Other threats to the least tern include shoreline hardening, mechanical raking, oil spills, response to oil spill events, and increased presence of domestic animals (Defeo et al. 2009).

Conservation and Management

The least tern is protected by the U.S. Migratory Bird Treaty Act. It is also protected as an Endangered Species (Midwest and Great Plains states only) by the Federal Endangered Species Act and as a State-designated Threatened species by Florida’s Endangered and Threatened Species Rule.